The present application relates to an input device suitable for a mobile phone, a digital camera, an information processing apparatus, or the like having a display screen which is touched to enter information, a storage medium, an information input method, and an electronic apparatus. More specifically, the present invention relates to an input device including a controller which provides display and input control, in which the area and/or brightness of a light-shielded portion of the display screen that is formed by an operating member is detected and the detected area and/or brightness is compared with a predetermined threshold value to select a desired input mode from among a plurality of input modes to implement input processing for each stage of operation according to a pressing state of the operating member, resulting in an improvement in operability.
Recently, users or operators have loaded various kinds of content into portable terminal apparatuses such as mobile phones and personal digital assistants (PDA) for use. Such portable terminal apparatuses are provided with an input device. The input device generally includes an input unit such as a keyboard or a JOG dial, and a display unit such as a touch panel.
Recently, optical touch panels employing liquid crystal panel technology have been available as touch panels suitable for input devices. An optical touch panel includes, on a liquid crystal display surface thereof, a light-shielding detection surface having a plurality of optical sensors (photosensors), and input information is obtained from a light-shielded portion formed by a user's finger.
A planar display device using this type of optical touch panel and an image obtaining method therefore are disclosed in Japanese Unexamined Patent Application Publication No. 2006-238053 (pages 4 and 5, FIG. 62). The disclosed planar display device includes a calibration unit that controls a control signal for photosensor pixels. In order to specify the position of a light-shielded portion, a read signal of each of the photosensor pixels is detected and a control signal for each of the photosensor pixels is controlled on the basis of the detected read signal so that the size of the light-shielded portion can be reduced to obtain one area. This structure allows accurate detection of the position of a light-shielded portion formed by an object.
An optical input device and information input method of the related art will be described briefly with reference to the drawings. FIGS. 15A and 15B are diagrams showing an example structure of an input device 200 of the related art. Referring to a block diagram shown in FIG. 15A, the input device 200 includes a display unit 201, a backlight 202 stacked below the display unit 201, a controller 203 that controls the display unit 201 and the backlight 202, and a storage unit 204.
The display unit 201 includes a plurality of pixels 210 arranged in a matrix. Referring to a schematic diagram shown in FIG. 15B, each of the pixels 210 includes a display color filter 211, an optical sensor 212 for detecting a light-shielded portion, a capacitor, and a wiring region 213. The pixels 210 emit light of colors in response to a control signal of the controller 203. The pixels 210 further detect a light-shielded portion and output the detection result to the controller 203.
In a case where the input device 200 having the structure described above performs input processing, first, the controller 203 controls the display unit 201 and the backlight 202 to perform display processing using the color filters 211 according to a display program stored in the storage unit 204.
An operator views images displayed on the display unit 201, for example, button icons, and touches a desired button icon with their finger. The display unit 201 detects a light-shielded portion formed by the finger using the optical sensors 212, and outputs the detection result to the controller 203. The controller 203 performs input processing according to the detection result and a program for input operations, which is stored in the storage unit 204. Further, the input device 200 sequentially performs difference determination, coordinate setting, and touch determination.
FIG. 16 is a diagram showing an example of difference determination performed by the input device 200. When a finger touches the display unit 201 shown in FIG. 16, a light-shielded portion 220 is formed at a touched portion of the display unit 201. The controller 203 detects a reduction in brightness and determines the light-shielded portion 220 on the basis of the reduction in brightness. The controller 203 also detects brightness levels of all the pixels 210, and determines a difference brightness level X=|Xn−Xave| between an average brightness level Xave of the detected brightness levels of all the pixels 210 and a brightness level Xn of a pixel 210 that is located within the light-shielded portion 220. The controller 203 further performs difference determination to compare the difference brightness level X with a predetermined threshold value Xth. If the difference brightness level X is greater than the threshold value Xth, the controller 203 performs coordinate setting.
In coordinate setting shown in FIG. 17, the controller 203 defines a centroid 221 at the center of the light-shielded portion 220. After the centroid 221 is defined, the control device 203 starts touch determination.
In touch determination shown in FIG. 18, the controller 203 monitors changes in the difference brightness level X at the centroid 221. The controller 203 observes a relational characteristic of a derivative value (dX/dt) of the difference brightness level X with respect to time t shown in FIG. 18, and determines, for example, input processing at time t1 indicating an inflection point of the gradient of the characteristic. At time t2 indicating an inflection point at which the gradient disappears, the input processing is terminated. The input processing based on difference determination, coordinate setting, and touch determination is implemented in the following procedure.
FIG. 19 is a flowchart showing an example of an input process of the input device 200. Referring to the flowchart shown in FIG. 19, in step G1, the controller 203 executes difference determination to constantly compare the difference brightness level X with the threshold value Xth. When the difference brightness level X becomes greater than the threshold value Xth, the process proceeds to step G2.
In step G2, the controller 203 defines the coordinates of the centroid 221 of the light-shielded portion 220. Then, the process proceeds to step G3. In step G3, the controller 203 executes touch determination. When the gradient of the relational characteristic (see FIG. 18) of the derivative value (dX/dt) of the difference brightness level X with respect to time t is inflected or changed at the centroid 221, the control unit 203 detects the time t1 at which the inflection starts. After the time t1 is detected, the process proceeds to step G4, in which the controller 203 determines and executes input processing corresponding to a button icon displayed at the centroid 221. If no inflection is detected for the gradient of the derivative value (dX/dt), the process returns to step G2, and coordinate setting is executed again. After the input processing is executed in step G4, the process returns to step G1, and the difference determination is resumed.
Alternatively, after input determination is performed, processing similar to the processing of step G3 may be executed to detect the time t2 at which the gradient of the characteristic of the derivative value (dX/dt) disappears. In this case, it can be determined that the pressing of the button icon ends at time t2.